Numerous procedures have been developed that involve the percutaneous insertion of a medical device into a vessel. Such a device may be introduced into the vessel by a variety of known techniques. For example, a wire guide may be introduced into a vessel using the Seldinger technique. This technique involves making a surgical opening in a vessel by a needle and inserting a wire guide into the vessel through a bore in the needle. The needle can be withdrawn, leaving the wire guide in place. An introducer device is then inserted over the wire guide and into the vessel. The introducer device may be used in conventional fashion to insert a variety of types of medical devices, such as catheters, cardiac leads, balloons, stents, stent grafts, and the like.
One of the challenges associated with endoluminal procedures is controlling the flow of bodily fluids within the introducer device during the procedure. Haemostatic devices and valve systems control the flow of blood through an introducer. US-A-2007/0078395 entitled “Haemostatic Valve System”, the disclosure of which is incorporated herein by reference, discloses numerous examples of haemostatic valve devices and systems that use disk valves to control fluid flow. US-A-2007/0078395 discloses, among other things, disk valves with holes that are offset from the radial center of the disk. In some examples, a valve system includes several such disks, aligned so that the holes are not substantially overlapping. Additional valve disks may be added to improve the pressure rating of such a valve system.
Using a large number of disk valves to provide a desired seal can present challenges. For example, as the number of disk valves increases, the total force required to insert a medical device through the valve system may increase. In addition, even when the valves are in a “closed” configuration, the holes in the disk valves remain open and may provide a pathway for leakage through the haemostatic device.